How to fix Avast Antivirus High CPU Usage

So a while back, I noticed that my CPU performance was decreased. I tested using wPRIME running a 32M benchmark. Without an Antivirus installed, I would get a score of 4.9 seconds, with Avast Antivirus Pro installed, I would get 7.5 seconds (the lower the score the better).

No help was offered and I was just told that any Antivirus would cause a small hit on the CPU performance.

I then installed NOD32 and Kaspersky Antivirus (separately off-course) and benchmarked again but I would get 5 seconds in wPRIME so that was all good and the issue seemed to only be there when Avast Antivirus was installed.

I then submitted a support ticker to Avast which as usual, took almost 2 weeks to be answered.

They suggested to change a few things which I did and now my CPU performance is back to normal, I am getting 5.3 seconds in wPRIME so a 0.3 seconds performance hit is fine.

Here are the suggestions from avast! Support to remedy this problem whilst not really affecting your security:

Let's try to make Avast running faster by removing some additional features and adjusting few settings. Please follow these steps to do so:

First please repair and update your Avast installation:
Click on Start > Settings > System > Apps & features > Avast installation > Click on "Uninstall" > REPAIR > Continue.
After the repair, please make sure that you have the most recent version of Avast - 2016.11.1.2253.
To do that, please open Avast and go to > SETTINGS > Update > Program > Update and update your Virus definitions as well.
Restart your computer.

After that please disable few additional Avast features:
Go to Start > Control Panel > Uninstall a program (Programs and Features, Add or Remove Programs)
Select Avast and click on Uninstall/Change.
In the Avast window that appears click on "Modify" > Continue > now under "Tools" uncheck the following:- Browser protection
- Avast SecureLine
- Cleanup
- Passwords
- Secure Virtual Machines (if present)
- Secure DNS
After that click "Continue" and after changing of the product will finish, restart your computer.

Kaspersky use to use 90-100% during a scan, Avast is super light weight compared to that.

I just checked Taskmanger and it has avast using 0% cpu, as it`s not scanning at the moment, when it does scan it might go to 25% but for 15min or so and then stops, I suppose how long the scan takes depends on how fast you cpu/hdd/ssd is and how many files it has to search though.

Kaspersky use to use 90-100% during a scan, Avast is super light weight compared to that.

I just checked Taskmanger and it has avast using 0% cpu, as it`s not scanning at the moment, when it does scan it might go to 25% but for 15min or so and then stops, I suppose how long the scan takes depends on how fast you cpu/hdd/ssd is and how many files it has to search though.

John.

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The right way to test it is, run wPRIME 32M benchmark with all threads which should be 8 if you have a 4 core CPU(go to settings in wPRIME) with avast! installed, then uninstall Avast and run the benchmark again, not immediately after a restart but after a few mins of being idle then see

PS: Disabling all Avast Shields doesn't count, it has to be uninstalled to see the difference before/after, if you have time to do this that is, maybe take an image before uninstalling it

As always, your mileage may vary. I've seen people say they dumped Avast because it was causing high CPU usage on their laptops and at the same time having tested multiple solutions, I chose Avast to run on my Atom-powered convertible, exactly because it has low CPU and very low RAM footprint while providing very good security.

I'll check those recommendations though - I think I might want to consider disabling "intelligent stream scanning" as Avast tends to eat up quite a lot of CPU when I'm downloading multiple files @ 100mbps. I'm guessing that's the reason - it attempts to scan multiple files at the same time coming at it at a steady 12MB/s

As always, your mileage may vary. I've seen people say they dumped Avast because it was causing high CPU usage on their laptops and at the same time having tested multiple solutions, I chose Avast to run on my Atom-powered convertible, exactly because it has low CPU and very low RAM footprint while providing very good security.

I'll check those recommendations though - I think I might want to consider disabling "intelligent stream scanning" as Avast tends to eat up quite a lot of CPU when I'm downloading multiple files @ 100mbps. I'm guessing that's the reason - it attempts to scan multiple files at the same time coming at it at a steady 12MB/s

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Good idea, please try the above recommendations and tell us if you see a difference. As support said, this will not lower your security because once the file is downloaded, if it was malicious, the active file shield will block it anyway so no harm done.

I personally dislike programs which do HTTP scanning, like I have a NOD32 license for 10 users valid until 2020 which is collecting dust as it slows down everything for me, internet browsing, downloads, etc. wish I could sell it

Yeah, I have use Avast on my Atom cpu table as well, no high cpu usage on it`s tiny little 900 passmark cpu score, my i3 i am using now gets around 2500 points and that is quite low to most modern cpu`s

Those that use torrent downloading apps can expect to have high anti-virus cpu usage as all files need to be scanned and zip files are extracted and files scanned individually in the background this can use a lot of cpu power.

John.

EDIT: Hi i found this 2015 AV comparison test, and they also rank them by cpu usage.

I'm afraid the support is wrong in this case.
You are assuming that the malicious code always has to be written to disk; if it is, then yes, the File System Shield (probably, because it has lower sensitivity than Web Shield) detects it. However, some malicious content (let's say in HTML or script form) may be interpreted/run by the browser without (or before) being written to disk

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Can you please delete this thread as I don't want to cause any security risk to anyone.

Let's leave it - it's valuable to know both what to and what not to do. Someone may come across it and find it valuable - granted not the way first intended.
Also Some of these tips from support remain valid - only intelligent scanning and script scanning should not be switched off it said moderator is right.